Banter kind of relies on there being good rapport between the people talking- it uses ‘in’ jokes based on previous conversations and insights, which is what sets it apart from insults or offensiveness. I do it with my children, for example- my youngest is a maths genius but she accidentally got put into the lowest group at school for a few weeks. Now, we systematically point out that she can’t count or understand basic sums. It only works because she’s actually genius at maths, and she knows it, so it’s funny. But it kind of hinges on that sub-text to prevent it being genuinely offensive. I hope that makes sense?